I’ve always had a brain that was wired for languages, so studied French and German to degree level, did Russian at GCSE, a couple of years of Latin at school, and cobbled together some Italian and Spanish for holidays. Because of that I can read many European languages well enough to get the gist without bunging them through DeepL. And I’ve found it useful professionally and personally because even where other people do speak English, they always appreciate an effort to speak their own language. It’s seen as good manners when so many UK and US English speakers are arrogant enough to assume they don’t need to bother.
I use both French and German for work, and it has definitely given me opportunities I wouldn’t have had without this fluency.
I started learning Japanese for work, because I was working for a Japanese company and most of the team out there don’t speak English. Turns out that’s not so uncommon in Japan, where the statistics on English speaking are very different to those in Europe and other parts of the world. Even as someone who is a natural at languages, Japanese is so very different to European languages that it even puts learning 48 adjective endings for Russian into perspective. Learning Cyrillic was a lot easier than picking up both hiragana and katakana, alongside kanji.
I’m not sure it’s as useful to learn Mandarin or Hindi as it is to learn a language you can commit to and learn for the love of it, knowing you’ll have the opportunity to speak it and maintain it. Especially if languages aren’t really your thing. I look at my husband, who relies on me whenever we’re abroad, and my son, who takes after his dad on languages, and I think either of them could learn maybe one other language well if they had the chance to use it regularly in everyday life, but not otherwise. Hindi and Mandarin would likely be beyond them, but a European language that they might get to use? Still better than no language learning at all.
I have a long way to go before I’ll have mastered Japanese, but I will keep going with it. In my fifties now, so not sure whether I’ll be adding any other languages to the repertoire, or just deepening my knowledge of other European languages. I’m tempted by Mandarin, Arabic and Korean, but I want to get better at Japanese before muddying the waters with another one. At least with Mandarin, I have the crossover of kanji from Japanese, so there is some knowledge I can reuse.
Finally, as far as apps are concerned, I use Busuu rather than DuoLingo, because it goes deeper into the grammar, and I still find that essential for learning a language versus parroting a few phrases. I find it a good support alongside the lessons I do with my Japanese teacher because it’s more up to date on vocabulary than the traditional Minna No Nihongo textbook. But I have also found watching Japanese TikTokers on lives has been a good way of getting my ear in. So
many more tools available to help these days :)